Thanks again Tim! It worked. Last night we had a change to rejoin the clearpass server to the domain. Once done, authentication via AD worked.
It was showing the server as joined to the domain. Looking further in AD we did not see the server. I tried to leave the domain but I kept getting an error (suspecting because it wasn't being seen on the domain within AD). So we just hit join domain and entered in the same domain info and it joined just fine.
Thanks again for the help!